Semiconductor devices are found in many products in the fields of entertainment, communications, networks, computers, and household markets. Semiconductor devices are also found in military, aviation, automotive, industrial controllers, and office equipment. The semiconductor devices perform a variety of electrical functions necessary for each of these applications.
The manufacture of semiconductor devices involves formation of a wafer having a plurality of die. Each semiconductor die contains hundreds or thousands of transistors and other active and passive devices performing a variety of electrical functions. For a given wafer, each die from the wafer typically performs the same electrical function. Front-end manufacturing generally refers to formation of the semiconductor devices on the wafer. The finished wafer has an active side containing the transistors and other active and passive components. Back-end manufacturing refers to cutting or singulating the finished wafer into the individual die and then packaging the die for structural support and environmental isolation.
One goal of semiconductor manufacturing is to produce a package suitable for faster, reliable, smaller, and higher-density integrated circuits (IC) at lower cost. For applications requiring high-density components, e.g., stacked memory devices or internal stacked modules (ISM), it is desirable to provide interconnect structures on front and back sides of the semiconductor package. Bond wires are commonly used to interconnect the stacked packages. However, bond wires have a loop height control requirement, which causes the semiconductor package to have an undesirable thickness. The long and uneven lengths of the wire bonds also exhibit differing propagation delays which causes timing issues in high-speed applications.
A need exists to form ISM packages having an interconnect structure on both sides of the package without using bond wires. The interconnect structure should allow for thinner packages and even propagation delays.